1. Field of the Disclosure
This disclosure generally relates to an interactive device and, more particularly, to a displacement detection device that may dynamically select pixels of interest in the image frame to accordingly calculate the displacement.
2. Description of the Related Art
The conventional optical mouse generally includes a light source, an image sensor and a processing unit and is configured to be operated by a user on a work surface. The light source is configured to illuminate the work surface. The image sensor is configured to receive reflected light from the work surface and to output image frames. The processing unit is configured to calculate a displacement of the optical mouse with respect to the work surface according to the image frames outputted by the image sensor, e.g. calculating the displacement according to the correlation between the image frames.
In the conventional optical mouse, the image sensor is configured to detect reflected light from the work surface. Therefore, when the image quality of the image frames captured by the image sensor is poor, it may not be able to calculate the displacement correctly.
For example referring to FIG. 1, an optical mouse generally includes a light source 81 configured to illuminate a work surface 9 through a lens 82, and the reflected light from the work surface 9 is received by an image sensor 84 through another lens 83. In assembling the optical mouse, the image sensor 84 may not be exactly disposed at an expected position. For example, if the image sensor is disposed at the position 84′ rather than at the position 84, the image quality of the image frames formed by capturing the reflected light of the work surface 9 by the image sensor may be poor and the poor images may lead to errors in calculation.
In addition, even though the image sensor 84 is exactly disposed at the expected position in assembling, the imaging may still have a position deviation when the optical mouse is operated on different work surfaces. For example referring to FIG. 2A, it shows a schematic diagram of the optical mouse operated on a surface of a glass in which reflected light of the work surface 9 still can be received by the image sensor 84. However, when the optical mouse is operated on a surface of another glass having a larger thickness as shown in FIG. 2B, the image sensor 84 may not able to receive the reflected light of the work surface 9 correctly such that the image quality is decreased and errors may occur in calculation.
Accordingly, the present disclosure further provides a displacement detection device that can be operated on different work surfaces and can effectively overcome the low image quality caused by the assembling error.